incubator-general mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Reto Bachmann-Gmür <>
Subject [VOTE] Accept Apache Clerezza into the incubator
Date Mon, 23 Nov 2009 18:32:12 GMT
Please vote on accepting Apache Clerezza for incubation at the Apache
Incubator. The full proposal is available at the end of this message and
as a wiki page at
<>. We ask the Incubator PMC
to sponsor it, with Bertrand as the Champion, and Gianugo, Niclas, Ross,
Karl and Reinhard volunteering to be Mentors.

Please cast your votes:

[ ] +1, bring Clerezza into Incubator
[ ] +0, I don't care either way,
[ ] -1, do not bring Clerezza into Incubator, because...

The vote is open for the next 72 hours and only votes from the Incubator
PMC are binding.

- - - - - - - - - -


Clerezza is an OSGi-based modular application and set of components
(bundles) for building RESTFul Semantic Web applications and services.


Clerezza can be used as a platform providing all the compile and runtime
requirement for building semantic applications, or used as individual
bundles within an OSGi framework, e.g. Apache Sling, Apache ServiceMix,
or the Eclipse platform.

Clerezza provides:

    * An API modeling the W3C RDF standard without any vendor specific
    * Adapter for various triple stores including Sesame, Jena TDB, and
    * Front-End adaptors, currently to run applications written against
the Jena API. Support for RDF2Go is planned.
    * A JAX-RS implementation designed to work in an OSGi environment
and allowing to provide Root-Resources as OSGi services.
    * Web access to RDF graphs, including a SPARQL-Endpoint.
    * Extensions to JAX-RS allowing to bind Root-Resource classes to
specific RDF-Types rather than to URI-Paths.
    * Templating mechanism (Renderlets) allowing to render RDF resources
returned by JAX-RS resource methods to various formats

      Support for Scala for writing modules, ScalaServerPages to easily
write renderlets, DSL for accessing graphs.
    * Authentication and authorization based on JAAS and OSGi
Conditional Permission Admin
    * Support for user bundles: Users can have a permission to upload
their own sandboxed bundles. The URI space these bundles are allowed to
register their JAX-RS resources can be limited with a prefix.
    * Scripting: Scripting based on javax.script (currently support for
JRuby and Scala)
    * Documentation: Bundles can provide their documentation in RDF.
These are used for online documentation as well as for building Maven
sites (with a Maven reporting plugin)

The RDF abstraction layer can be used independently of other aspects of
Clerezza. It allows applications to be written regardless the used
backend. In its purpose, it is similar to RDF2Go, but provides a
significantly more modular interface allowing e.g. to independently
switch the storage, querying, or serialization layer. Furthermore, it
doesn't introduce concepts alien to the RDF model such as blank node
labels, but is in its core strictly limited to RDF semantics.

The JAX-RS implementation can also be used independently of any other
components. It allows OSGi services to provide a RESTful interface to
their methods. By being based on wymiwyg WRHAPI, it can run both on the
default OSGi Web Service as well as on a jetty instance listening on a
different port.


The current web trends focusing on information sharing, interoperability
and collaboration. Therefore the behaviour of the end-user has changed
over the last years: end-users not only consuming information they also
producing content anytime anywhere - in contrast to non-interactive
websites where users are limited to the passive viewing of information
that is provided to them. Since the end-users are sensitized to the
possibilities of the web the web application requirements increases.
Examples of such applications are social-networking sites, wikis, blogs
and mashups.

The REST paradigm and Semantic Web technologies support these trends and
form the basis for the upcoming Web of Data (a.k.a. linked data, Web
3.0). They change the paradigms for developing complex Web applications.
Clerezza allows to develop applications that integrate perfectly in the
Semantic Web providing all accessible resources in machine
understandable formats without imposing additional burdens on the
developer. Additionally, thanks to the flexibility of the RDF model used
as back-end, some tedious database related tasks required for
traditional Web application development are no longer needed.


Most Web application framework are not designed to leverage the full
power of HTTP but often try to reproduce non Web design patterns for the
Web environment. In general, application frameworks are oriented towards
relational or hierarchical data structures. While attempts to overcome
this such as Drupal have become very popular, they do not at their core
base on the stack of Semantic Web standards. Clerezza will prove that
the flexibility of the RDF doesn't result in increased complexity, but
on the contrary allows for fast prototyping and development.

Initial Goals

The initial goals for Clerezza are:

    * Donate the existing codebase and import it.
    * Setup the incubation infrastructure (svn repository, build system,
website), so we can run continuous builds with automated tests and
publish all available documentation.
    * Get people involved in advancing the code base in different
directions, integrating it with other projects at Apache.
    * Prepare for an initial release that demonstrates the systems core

Current Status

The current codebase is developed and tested using Apache Felix. It has
been developed intensively and reviewed at trialox since August 2008
using Scrum, with a development process emphasizing individual
accountability and reviews. We have internally demonstrated that we can
release codes as scheduled. Platform core functionalities are available,
however the need for new features may arise, performance and robustness
could be improved. Incomplete documentation for the project is available
with the individual artifacts, both in the generated maven sites as in a
version available exposed by Clerezza at runtime. We also have a wiki at with some information mainly on the development
process. We also use mailing lists for communication among developers
and users.


The core developers understand what it means to have a process based on
meritocracy. We will provide continuous efforts to build an environment
that supports this, encouraging community members to contribute.


Trialox has been developing the current codebase since August 2008.
Trialox was founded in partnership with the University of Zurich and
could benefit from previous research work at the Department of
Informatics. Part of the team from the beginning was Reto Bachmann Gmür
who has been developing open source Semantic Web applications for many
years, including working with the Jena team at HP Labs.

Trialox has contributed to the JAX-RS specification. Some of the code
written by trialox is used by Open Source projects such Paxle and Gradino.

Clerreza is used by globally active non-profit organisations such as the
WWF. These organisations have strong developer networks including
motivated volunteers, which will contribute to Clerezza.

Core Developers

People from Trialox, the University of Zurich, as well as partner
companies of Trialox have contributed to the project. Currently, the
following persons are core developers of Clerezza:

    * Manuel Innerhofer, Developer at Trialox since November 2008.
    * Hasan Hasan, Developer and Senior Researcher at University of
Zurich since 2006, developing Clerezza since August 2008. His current
research interests cover P2P networking, Service Level management, and
Internet security.
    * Tsuyoshi Ito, Developer and Scrum Master at Trialox, developing
Clerezza since August 2008. He has researched at the University of
Zurich since 2005. His research interest was computer-supported Learning
(Educational Engineering)
    * Reto Bachmann-Gmür, Developer and Architect at Trialox, developing
Clerezza since August 2008.


We provide a launcher which runs Clerezza's bundles within Apache Felix.
We also provide feedback about the usage of Apache Felix and its
components including the framework security via the mailing list. For
building Clerezza's bundles we use Apache Maven and various plugins. We
also have developed a plugin to help managing projects which contain
ontologies, so that Java classes representing those ontologies can be
pre-compiled. Other projects which based on Web services and/or RDF can
benefit from Clerezza or its specific bundles. We are open to
collaborate with other Apache projects which can benefit from
functionality provided by Clerezza. Clerezza has the advantage of being
very modular and independent of application frameworks, thus can be
easily integrated with other Apache projects. UIMA and Tika come to
mind, as they would help extract semantic information from various data
types and formats. An alignment to the JAX-RS implementation in Apache
CXF could not only help removing the dependencies to the CDDL-licensed
code taken from Jersey but also help providing a fully framework
independent implementation with a larger group of developers and thus
higher quality.

Known Risks

The current team of Clerezza core developers is small, but being an
innovative project in the semantic "space", we are confident that
Clerezza can attract new developers.

Clerezza has been started as an Open Source project providing mercurial
repository for public access to source codes and also a publicly
accessible JIRA instance for issues tracking. Clerezza is licensed since
project begin under Apache License version 2.0. Some of the initial
committers already have strong experiences with Open Source software
development. Others, while not being totally inexperience, are willing
to learn.

The risk that Clerezza will be an orphaned product is considered small.
Three main factors will avoid this to happen:

    * Trialox and its founder Getunik have a vital interest in continuos
development in this open source foundation
    * Clerezza is used as foundation for research as well a student
projects at the University of Zurich
    * There is a strong commitment by Reto Bachmann-Gmür to maintain
    * WWF expressed their support to deploy Clerezza


A small set of further documentation is available under the following links:


Initial Source

Clerezza has been in development since mid 2008. Public access to the
source is provided through

Source and Intellectual Property Submission Plan

The current codebase is owned by trialox, and will be donated together
with its documentation. We will get the paperwork out of the way as soon
as possible.

External Dependencies

There are quite a few open source libraries already used. They have
Apache compatible licenses, with one issue to solve around Jersey which
is CDDL.

The libraries, their sources and licenses are listed here:

Apache Felix, ASL:

    * Framework
    * Framework Security
    * Configuration Admin
    * maven-scr-plugin
    * maven-bundle-plugin

OSGi Alliance, ASL:

    * Core
    * Compendium

Apache Maven, ASL:

    * apache-maven

Eclipse, ASL:

    * Jetty


    * Pax Exam
    * Pax Logging
    * Pax protocol mvn-uri


    * wrhapi
    * wymiwyg-commons

jQuery, MIT license:

    * jquery

Hewlett-Packard Development Company, BSD License:

    * Jena (for the optional jena forntend adaptor, as well as for jena
based serializer/parser)
    * Jena TDB (for the optional tdb backend adaptor), BSD license (for the optional sesame backend adaptor):

    * Sesame, Open Software License ("OSL") v. 3.0 (for the optional
mulgara backend adaptor):

    * mulgara

XSite (, BSD license:

    * xsite-maven-plugin

Jersey (, CDDL license

The current code bases on code licensed under the CDDL, according to we understand we have to get rid
of these before making a release, or redistribute in binary form only.
The following files are affected.


Required Resources

Mailing lists:

    * clerezza-dev
    * clerezza-commits
    * clerezza-user (only after leaving the incubator)



Issue Tracking:

    * JIRA: Apache Clerezza (Clerezza)

Initial Committers

These committers have either worked on the initial codebase (Reto,
Immanuel, Tsuy, Hasan) or expressed an interest in extending the project:

    * Reto Bachmann-Gmür (trialox)
    * Manuel Innerhofen (trialox)
    * Tsuyoshi Ito (trialox)
    * Hasan Hasan (University of Zurich)
    * Bertrand Delacretaz (ASF member, Day Software)
    * Michael Marth (Day Software)
    * Tommaso Teofili (Apache UIMA committer)


Manuel Innerhofen, Tsuyoshi Ito and Reto Bachmann-Gmür work at trialox
and might get paid to work on Clerezza.

Hasan Hasan from University of Zurich is paid to work in a project that
is based on Clerezza.

Michael Marth and Bertrand Delacretaz work for Day Software.


We have approached both the champion and an initial list of mentors that
have agreed to mentor this project.


    * Bertrand Delacretaz


    * Gianugo Rabellino
    * Niclas Hedhman
    * Ross Gardler
    * Karl Pauls
    * Reinhard Pötz


    * Apache Incubator

Reto Bachmann-Gmür
Tel: +41445005015

To unsubscribe, e-mail:
For additional commands, e-mail:

View raw message